One of the main reasons for anemia in premature infants is blood withdrawal from them for diagnostic purposes. During their first days of life, infants weighing less than 1500 grams, whose blood volume is less than 120 ml, are often subjected to blood withdrawal, as a result of which they inevitably have to be transfused with packed-cells. Some infants receive the equivalent of a double- or triple-volume red cell exchange transfusion as a result of blood sampling for laboratory tests. The premature infants are exposed to all of the side effects of blood transfusions, including infections due to agents transmitted by blood (CMV, HIV, hepatitis), volume overload, mechanical erythrocyte injury, alloimmunization, and more.